1. Field of the Invention
The present invention relates to a nail gun that drives a nail through, for example, the hole of a connection clasp and to a nail gun that can accurately drive nails into a desired drive position.
2. Description of the Related Art
A variety of different types of clasp fixing nail guns have been proposed. U.S. Pat. No. 5,193,730 discloses a nail gun that separates nails one at a time from a nail band and supplies the nail to a nail injection hole of the nosepiece. The nail tip is protruded from the end of the nosepiece before the nail gun drives the nail.
The nail gun further has a safety mechanism with a work-piece contact member, an intermediate lever, and an operation lever. The work-piece contact member extends from the nose of the nail gun to the base of the intermediate lever. When the trigger of the nail gun is pressed, the operation lever moves toward or away from an activation plunger, depending on the position of the work-piece contact member and the intermediate lever. That is, the work-piece contact member is raised into its lowermost position as long as the nose of the nail gun is not pressed against a work piece. If the trigger is pressed at this time, the intermediate lever pivots greatly and guides movement of the operation lever away from the activation plunger. On the other hand, when the nose of the nail gun is pressed against a work piece, the contact member is raised into its upper position. If the trigger is pulled at this time, pivoting movement of the intermediate lever is restricted so that the operation lever moves into contact with the activation plunger, thereby setting off a nail driving operation. In other words, the safety mechanism prevents the nail gun from firing when no work piece is present by changing the pivot path of the operation lever.
It is conceivable to lengthen the stroke of the work-piece contact member, that is, the distance that the work-piece contact member can move, by increasing the length of the intermediate lever. However, the intermediate lever can only be lengthened within the movement range of the trigger. Therefore, it is difficult to lengthen the stroke of the work-piece contact member. As a result, the lower end of the work-piece contact member must always be positioned fairly near the nail ejection opening, even when the work-piece contact member is at its upper dead center. This makes it difficult to see the nail tip so that it is difficult to position the nail at the precise position where it is to be driven into the work piece.
Also, the intermediate lever and the operation lever are provided in a narrow space above the trigger and operate in a fairly complicated manner against urging force of springs. A slight error in component or position dimensions, abrasion caused by friction, or dust, dirt, and the like clinging to components could easily become the cause of misfires. As a result, reliability of the nail gun suffers.
It is an objective of the present invention to overcome the above-described problems and provide a nail gun that more easily allows visual confirmation of the nail tip location and that uses a simpler configuration, which improves reliability by helping prevent the danger of misfires.
In order to achieve the above-described objective, a nail gun according to the present invention includes a body; a nail ejection portion connected to the body and having a tip formed with a nail ejection hole; a magazine connected to the nail ejection portion, the magazine feeding nails one at a time to the ejection portion; a blade supported in the body capable of reciprocal movement in opposing first and second directions and, when activated, driven in the second direction to the nail ejection portion to strike a nail in the nail ejection portion and to eject the nail through the nail ejection hole; an activation switch having a protruding plunger, the activating switch activating the blade when the plunger is pressed inward; a trigger having a trigger pivot end and a trigger free end, the trigger being supported pivotably on the body at the trigger pivot end; a trigger arm positioned within the trigger, the trigger arm having a trigger-arm pivot end, a central portion, and a trigger-arm free end, the trigger-arm pivot end being pivotably disposed at a position between the plunger and the trigger free end, the central portion being disposed at a position adjacent to the plunger; a safety portion having a first-side end disposed in contact with the trigger-arm free end and a second-side end positioned near the nail ejection hole, the safety portion being supported capable of reciprocal movement in the first and second directions between an upper dead center and a lower dead center; and urging means for urging the safety portion into the upper dead center; wherein when the trigger is pivoted on the trigger pivot end, pivoting movement of the trigger moves the trigger-arm pivot end to press the central portion of the trigger arm into contact with the plunger and, with the plunger serving as a fulcrum, to press the trigger-arm free end in the second direction against the first-side end of the safety portion.
With this configuration, a long stroke can be achieved for the safety portion. Therefore, the lower end of the safety portion can be separated from the nail tip in the initial condition, so that whether the nail tip is properly set in the clasp hole can be visually confirmed with ease. That is, the position where nails will be driven into the work piece can be accurately set.
Also, only the trigger arm is provided within the trigger and the safety portion is configured from only the upper safety portion and the lower safety portion. Operations are more reliable because the configuration is so simple.
If movement of the safety portion in the second direction is obstructed when the trigger is pivoted on the trigger pivot end, then the first-side end of the safety portion contacted by the trigger-arm free end serves as a fulcrum around which the trigger arm pivots with movement of the trigger, whereupon the central portion presses the plunger inward so that the activation switch activates the blade.
As a result, a nail driving operation can be reliably performed.